In reply to rosequartz...firstly, I am glad you are free of an abuser.

why would you voluntarily sign up for something like this?

Because BPD's have many positive traits. Your tone sounds extreme. I think that many BPD's are lovable, including me. The difference is I chose to not think of the label BPD as a threat, and I chose to investigate and get help. If a BPD person does not want to get help then yes, I would agree, either adapt to the behavior by putting up boundaries etc, or get out of the relationship.

Itried to fix it, realized there was no fix and I didn't want to spend my life being someone's scapegoat.....hopefully you will realize that before they've destroyed you.

See- that is the problem for the non-BPD: trying to fix someone else. The fix comes from within and with the aid of a counselor, and then the non-BPD person can be educated about where the BPD is at in their stage of "fixedness".
Ofcourse some BPD traits will not be "fixed", but do they need to be? Many people in society have maladaptive quirks we call "eccentric" and we don't lock them up. With good boundaries, we may even accept them. I think that BPD is something that both the BPD sufferer and the non-BPD have to first come to terms with and accept, then try to get help, then have some sense of resignation that this BPD may not ever be what society calls normal.